It's been a disappointing year for American cities seeking to curb violence via tough gun laws.

Since last June, when the US Supreme Court struck down key parts of the District of Columbia's gun-control ordinance, cities have seen the 20,000 local gun regulations enacted over the years begin to slip from their grip, one by one.

For years, strict gun laws in primarily Midwestern, Northeastern, and California cities have created an uneasy tension between the Second Amendment and crime-fighting realities on the ground. Then, the US Supreme Court, in a 5-to-4 decision, affirmed the constitutional right of individual Americans to own handguns, in a case known as District of Columbia v. Heller. In striking down parts of D.C.'s law, it opened the door to court challenges of other cities' ordinances restricting access to certain kinds of guns.

Gun-control laws in "New York and Chicago are next," says Bill Vizzard, a criminologist at California State University at Sacramento. Though the Heller ruling doesn't give a carte blanche right to "have a gun anywhere, under any circumstance," he says, its effect "could still be extensive. We just don't know yet how courts are ultimately going to interpret it."

Post-Heller, US appeals courts have divided over whether the ruling means that other city and state gun-control laws should be invalidated. The US high court could resolve the matter, but legal scholars say it's hard to tell if the justices are interested in setting a broad precedent on the issue.

The two laws in Philadelphia stuck down Thursday were enacted in 2008. One banned assault-style weapons, which are semi-automatic rifles altered to combat specifications. The other restricted an individual's ability to buy handguns to one a month.

Mr. Vizzard characterizes the gun rights movement as a long-term, deliberate, and scholarly based march akin to that of the civil rights movement. But the pro-gun legal effort, he notes, is moving counter to trends that show Americans becoming increasingly distant from their pioneer roots, with gun-rights stalwarts primarily consisting of middle-age and older white men.

That paradox puts more focus on the makeup of courts, including the US Supreme Court.

In January, Supreme Court nominee Sonia Sotomayor, as part of the Second Circuit Court of Appeals, was part of a majority that ruled against invoking the Second Amendment in a challenge to New York's ban on nunchaku sticks, a martial arts weapon. The ban stands.

The Pennsylvania high court ruled in 1996 that cities can't preempt the state's gun laws to create their own, but Philadelphia is now hoping that a court with a different makeup will rule differently, says Scott Shields, the lead National Rifle Association attorney.

Not all cities have lost in court. One challenge to Chicago's handgun ban was turned back earlier this month by the Seventh Circuit Court of Appeals.

Polls show that most Americans believe in the Second Amendment, but most also want stronger gun laws. The percentage of Americans who support an assault-weapons ban, however, has slid several percentage points in the past few years. In 2007, gun groups spent nearly $2 million to lobby Congress; pro-gun control groups spent $60,000.